Self-combustible solid charge operated engine starter



March 25, 1952 R. WARK 2,590,432

SELF-COMBUSTIBLE SOLID CHARGE OPERATED ENGINE STARTER Filed March 51,1950 Inventor ROBERT WARK Attorneys Patented Mar. 25, 1952SELF-COMBUSTIBLE SOLID CHARGE OPERATED ENGINE STARTER.

Robert Wark, Irvine, Scotland, assignor to Imperial Chemical IndustriesLimited, a corporation of Great Britain Application March 31, 1950,Serial No. 153,013 In Great Britain May 31, 1949 l Claims. 1

The present invention is concerned with a new and improved deviceoperated by a cartridge containing a self-combustible solid charge forengine starting and more,particularly for the starting of internalcombustion engines. The starting device in accordance with the presentinvention is especially suitable for use with cartridge containingself-combustible charges comprising colloided nitrocellulose, butselfcombustible charges of other kinds may be used in the cartridgesemployed if desired.

A cartridge operated starting device according to the present inventioncomprises in combination a firing chamber to accommodate a cartridge, aspring controlled non-return valve positioned in a housing and adaptedto release pressure within said housing, a pressure controlling orifice,a trap to prevent choking of said pressure controlling orifice, and abreech, the said pressure controlling orifice being positioned betweensaid trap and said spring controlled non-return valve.

It is desirable that the said firing chamber should have a safetyburning disc.

It is also desirable that the said housing should be provided with asafety burning disc.

To use the cartridge operated starting device of the invention thehousing thereof is attached to the cylinder head of an engine, either byscrewing it in or attaching it by a flange, so as to permit the gas fromthe cartridge to enter a conduit which is within the cylinder head andleads into the cylinder of the engine, preferably by way of thecombustion chamber or other ancillary chamber of said cylinder. Afterthe cartridge has been fired within said firing chamber of the devicethe pressure created therein opens the non-return valve and allows gasto enter the said combustion chamber or said other ancillary chamber ofsaid cylinder so as to develop a predetermined maximum pressure in saidcylinder. This causes the appropriate combustion of the engine to moveand thus to bring about the rapid rotation of the engine shaft.

The device of the invention is designed particularly to permit acartridge of the double base propellant type to burn within it at apressure of for example 1500 to 2000 lbs. per sq. inch in order toeliminate the objectionable residues which are formed when suchcartridges burn at lower pressures. As the pressure normally permittedin the cylinder is 1000 lbs. per sq. inch the pressure cont-rollingorifice is of such size with respect to the nature of the charge and theengine to be started that the pressure within the cylinder is neverabove 1000 lbs. per sq. inch.

The device of the present invention permits the gas evolved by a burningcartridge to be used efliciently and economically as it'acts directly onthe piston of an engine.

The invention will be better understood by reference to the diagrammaticdrawing accompanying the specification which illustrates in longitudinalaxial section one form of starting device in accordance with the presentinvention with a self-combustible gas producing charge positioned withinit.

In the drawing l is a tubular firing chamber member formed in thefashion of a T-piece, the wad of which is externally threaded at one endin order to cooperate with an internally threaded breech closure I9. Thegreater part of the cylinder bore of this firing chamber member lconstitutes the firing chamber, which extends for some distance beyondthe cartridge [6, containing the self-combustible gas producing chargeto be employed. Thereafter the diameter of the bore is somewhat reducedfor a short distance and again expanded as shown at 8 and 1 terminatingin an internally threaded portion, in order to permit the insertion andretention of a powder trap 6 of grid-like construction and a steel ringmember 4 having an axial throat 5 so that the powder trap extends for ashort distance into the empty portion of the firing chamber. Anemergency gas escape channel 9 of smaller diameter than the combustioncham-.

ber opens out in the stem of the T-piece to provide a shoulder andinternal thread for the seating and retention of an emergency gasrelease device of which the members consist of a disc I l, adapted toburst at a predetermined pressure, interposed between annular gaskets l0and [2, an externally threaded hollow stud bolt venting head l3 having acentral channel 14 of greater diameter than the channel 9 and ports l5radiating from the channel M to the atmosphere in a plane at rightangles to the axial channels 9 and M. The internal shoulder in the stemof the T-piece is accurately machined sothat the disc H between thegaskets I0 and I2 forms a gas-tight seal between the channels 9 and I4when the hollow stud bolt venting head 13 is screwed home.

2 is a valve housing member of cross-piece construction channelledthrough three of its arms to provide an internal bore substantiallygreater than that of valve stem 26 and through the fourth arm to adiameter sufficient to provide a sliding fit for said valve stem. One ofthe aforesaid three arms terminates in an externally threaded portionserving to cooperate with the internally threaded end of the combustionchamber member I, to retain the grid 6 and throated steel ring 4 inposition in the latter member. The channel through the opposite arm ofthe cross piece terminates in a shouldered and expanded portion adaptedto accommodate a relatively low pressure emergency pressure releasedevice constituted similarly to that provided in the combustionchamberand constituted by a sealing disc I la adapted to burst at apredetermined pressure interposed between two gaskets Illa and l2a andan externally threaded hollow stud bolt venting head [3a having an axialgas space [4a and ports l5a radially venting to the atmosphere in aplane at right angles to that of the ports I5. The third arm of thecross piece has a gas channel 32 of wider diameter than stem 26 of thevalve 2'! and at its end has a seating 24 for the valve. The channel 25extending from the throated ring i to the sealing disc Ila and thecommunicating channel 32 provide an expansion space for the gases fromthe cartridge IS.

The end of the arm accommodating the valve seat is threaded and shapedso as to enable it to be screwed into the cylinder head 3 of the engineor an extension thereof, and permit the gases to enter'through thechannel 28 into the cylinder head. The opposite arm of the cross pieceis externally threaded for a portion of its length and terminates in anannular cylindrical portion of reduced external thickness. A portion ofthe valve stem 26 emerging immediately beyond this extremity is ofreduced diameter but the valve stem terminates in a portion of the samediameter as the main portion of the stem. 29 is an internally threadedcap having a channel through its closed end and enclosing a split ring3! around the portion of the valve stem of reduced thickness, and aspring 30 in compression, so that when the cap 29 is screwed on to thethreaded portion of the cross piece the valve face is held in contactwith its seating. i1 is the brass base of the cartridge and i2 is thepercussion cap thereof. 20 is a striker normally held out of contactwith the percussion cap by means of the spring 2| and gland 22. strikerwith a hammer or the like the percussion cap ignites the charge in thecartridge i8, which conveniently comprises one or more massive pieces ofcolloided nitrocellulose, the gases from which build up a relativelyhigh pressure, suitable for the self-combustion of the colloidednitrocellulose charge in the combustion chamber, and pass through thegrid 6 which retains any dislodged large fragments of the burning powdercharge and thence through the throat 5 from which they emerge underreduced but still substantial pressure into the channels 25 and 32, as aresult of which they cause the valve 21 to leave its seating and flowpast it into the cylinder head and forcibly depress the piston of theengine. By the time the piston reaches its lowest position the charge inthe cartridge l6 has been wholly consumed. The energy transmittedthrough the piston to the fiy-wheel of the engine On striking the s.-

now causes the piston to commence to rise, and is sufficient to ensurethat the motion of the piston will continue until the engine fires andthe fallin pressure in the channels 25 and 32 consequent on thecessation of the self-combustion of the now wholly consumedself-combustible charge in the cartridge It, enables the spring 26 toeffeet the closing of the valve 21 so that there will be no blow back onthe compression stroke or after firing.

Should an excessive pressure develop in the channel 25 or the channel 32as a result of the combustion of the self-combustible charge in thecartridge [6, the safety disc Ila will burst and the gases vent throughthe ports l5a to the atmosphere. An excessive pressure might develop ifthe valve should become sluggish in its action as the piston of theengine should seize.

For example, in a device fashioned of high tensile steel for starting adiesel engine rated at 50 H. P. a device in accordance with theinvention attached to one of the cylinders could work at a maximumcombustion chamber pressure of 2000 lbs. per sq. inch and a maximumpressure 1000 lbs. per sq. inch on the cylinder to be put in motion. Thespring would be such that the valve 2'! opened under a pressure of lbs.per sq. inch and closed when the pressure in the channel 32 fell to 35lbs. per sq. inch, and the discs H and I to would be such as to burstrespectively at pressures of 3500 and 1750 lbs. per sq. inch.

What we claim is:

1. A cartridge operated starting device comprising in combination afiring chamber to accommodate a cartridge, a spring controlled nonreturnvalve positioned in the housing and adapted to release pressure withinsaid housing, a pressure controlling orifice, a trap to prevent chokingof said pressure controlling orifice, and a breech, the said pressurecontrolling orifice being positioned between said trap and said springcontrolled non-return valve.

2. A cartridge operated starting device as claimed in claim 1 whereinthe said firing chamber has a safety bursting disc.

3. A cartridge operated starting device as claimed in claim 1 whereinthe said housing is provided with a safety bursting disc.

4. A cartridge operated starting device as claimed in claim 1 whereinthe said firing chamber and the said housing are both-provided with asafety bursting disc.

ROBERT WARK.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 744,857 Cook Nov. 24, 19031,572,998 Harris Feb. 16, 1926 2,221,706 Havill Nov. 12, 1940 FOREIGNPATENTS Number Country Date 21,665 Denmark of 1916 524,454 Germany of1931

